Serial Attached SCSI (SAS) and Serial Advanced Technology Attachment (SATA) are two known communication standards for computer buses and/or networks. Connections according to these standards are often used to attach hard disk drives to host computers, but may feature other uses as well.
SAS and SATA feature signal communications in relatively high frequencies during normal operation. Also, SATA and SAS may feature data rates of 1.5 Gbps to 6 Gbps. The signals used by SAS and SATA during ordinary operations are referred to as in-band frequency signals. However, in some relatively rare occasions, SAS and SATA devices communicate using signals that are different than those used in ordinary communications. These signals are usually used during link initializations, and referred to as out of band (OOB) signals.
The existing SAS and SATA standards allow for communications only over relatively short distances due to the electrical properties of the physical communication systems required by those standards.